A projector is an image display apparatus that displays an image by projecting light corresponding to image signals that are obtained from an image supplying device such as a computer. Conventionally, a metal halide lamp such as an extra-high pressure mercury lamp has mainly been used for a light source of the projectors. Recently, a laser projector that uses laser beam as light of the light source has been proposed. The laser beam source has a high directivity which allows effective utilization of light as compared to a lamp. Moreover, a projector having a laser beam source has a simpler structure and high color reproducibility. Moreover, an optical system of the projector can be made small by the use of a laser beam source. Therefore, the laser projector has an advantage that the projector is small and light, and provides projection images with excellent color reproducibility, compared to a conventional projector that uses a metal halide lamp.
The laser beam used in the projectors is quite powerful. Therefore, if the laser beam that stops scanning due to malfunction and the like and directly falls on the eyes of the people standing or seating nearby, it affects the eyes. In addition, when laser beam is irradiated on an object having a high absorptance for longer than a certain time, there is a risk of ignition. Particularly, there is a fear that stopping of laser beam scanning may cause burning of the screen. Therefore, it is necessary to reliably prevent problematic situation from occurring by shutting down the laser beam production instantly when the laser beam stops scanning for any reason. The technologies that produce safer laser beams have been proposed in, for example, Japanese Patent Application Laid-Open Publication Nos. 57-60309 and 2001-267670.
However, the conventional technologies require to check that scanning of the laser beam is not carried out normally, and to undergo a processing path via a control circuit before shutting down the laser beam production. The shutdown of the laser beam production is not directly performed on the laser beam source but indirectly carried out via the control circuit. When the shutdown of the laser beam production is indirectly carried out, there may be a case where avoiding occurrence of problematic situation arising from a hitch of the control circuit itself is not sufficient. It becomes a problem to be exposed to laser beam, in particular, to laser beam with high power because the laser beam has a high directivity. Furthermore, it is possible to divert a laser beam source to other applications by taking it out of the projector on purpose. However, diverting such a laser beam source to other applications raises a further problem when the laser beam source is provided with high power. The present invention is carried out to solve the above problems and has an object to provide a projector with a high level of safety that reduces exposure to laser beam by directly shutting down the laser beam production when scanning of the laser beam is not carried out normally. Another object of the present invention is to provide a projector that makes it possible to reduce a possibility of diversion of the projector to other applications.